DE102009047495A1 - Electrohydraulic power supply for brake system of motor vehicle, has motor operated pressure sources and accumulators for supplying load upto higher pressure levels sufficient for areas of application - Google Patents

Abstract

The supply has a motor operated pressure source e.g. motor operated pump (2), and another motor operated pressure source and accumulators (10, 16) for supplying load (14) upto higher pressure levels sufficient for areas of application. The latter source is formed as a hydraulically operated pump. The load is designed as a brake system of a motor vehicle. The pump is provided for producing the high pressure level. An electrically switchable valve (6) is provided for switching the sources and/or accumulators. An independent claim is also included for a linear hydraulic drive.

Description

The The invention relates to an improved electrohydraulic power supply for at least one Consumers, in particular a motor vehicle brake system.

It For example, brake systems are known in which for energy supply Both a pneumatic brake booster, as well as an electric motor driven pump are used to a requested brake pressure to provide. It is a complete separation of at least two brake circuits provided. In other words, for everyone the brake circuits provided a separate pump. A double function of Pump, on the one hand as return pump in the context of anti-lock braking functions or as part of a driver-independent requested Pressure build-up requires compromises in system design and layout. There is therefore a need for an improved design or function the energy supply.

to Power supply of braking systems are also called electro-hydraulic Brake systems have been proposed, where appropriate, multi-flow running pumps are provided for charging a central high-pressure accumulator. These brake systems have not prevailed so far.

Of the Invention is based on the object, an improved power supply for at least one Consumers, for example Automotive brake systems, actuators or the like to create.

These The object is achieved by the Characteristics of claim 1 solved.

If the hydraulic system of one (or more) consumers only in rare operating situations a particularly high supply pressure needed it is energetically not optimal, this system permanently with the to provide maximum pressure. For power supply of hydraulic Discontinuous systems, such as braking systems, does it make sense to buffer energy? It is still often appropriate, the Keep energy in a hydraulic accumulator and not in one electrical energy storage, because then delivered higher power peaks can, as in a spontaneously retrieved electrical-mechanical-hydraulic Energy Conversion.

at The invention is therefore at least one further pressure source and / or a further pressure accumulator is provided, wherein the first pressure source or the first pressure accumulator the consumer (s) up to a first Supplied pressure level that for a certain scope is sufficient and that the further pressure source or the further pressure accumulator the consumer (s) up to a second, higher Supplied pressure level that for another area of application with higher pressure level is sufficient is.

So long the basic supply is sufficient, the hydraulic system with the pressure supplied to the first pressure source or the first pressure accumulator and the high pressure source remains uncoupled. If necessary one over the Basic supply beyond supply pressure is at least a further high pressure source or accumulator switched on, so that the pressure is increased to the maximum desired level can.

The The invention is based on the idea that the efficiency of electro-hydraulic Akuatorsysteme with hydraulic energy storage is greatest when the pressure level the energy storage as possible chosen low is. In known systems, the pressure level is the required maximum pressure established. In the invention, however, at least two different pressures are available be put into operation as needed, so that the leading to an efficiency reduction Use of a high pressure source to control the actuators in an area where a lower supply pressure is sufficient would, is avoided. In other words, it avoids having one High pressure source for supplying the consumer in a low pressure range is used and vice versa. This will be electrohydraulic Efficiency and thus increased efficiency. This does not need, as with known solutions, with loss of function be bought.

Though it is already known in brake systems, an insufficient pressure level with the help of an electric motor driven pump to the required value to raise. It must but extremely expensive electric motors be used, if you are not with the limited dynamics a standard drive satisfied. Furthermore, in these solutions is a uninterruptible and fail-safe power supply prerequisite for a safe Function. The occurring power peaks require a backup battery, to keep the on-board network load at a reasonable level. Because of the prescribed separation of the brake circuits must be for each Brake circuit to be provided a separate pump. Finally kick in these systems despite technically complex countermeasures undesirable Pressure pulsations on.

According to the invention, a hydraulic linear drive with seat valves is provided, the front may be used in particular in a brake system use.

Of the Hydraulic linear drive is characterized by a particularly simple Structure and ease of manufacture and is therefore special inexpensive. The pistons and seat valves of the linear actuator can be beneficial to the same Be arranged axis, the number of hydraulic connection holes can be reduced to a minimum.

embodiments The invention are illustrated in the drawing and in the following explained in more detail.

It show in the drawing:

1 a first embodiment of an electro-hydraulic power supply,

2 a second embodiment of an electrohydraulic power supply,

3 a third embodiment of an electro-hydraulic power supply,

4 a fourth embodiment of an electro-hydraulic power supply, and

5 an embodiment of a linear drive according to the invention, the z. B. for power supply (according to 2 to 4 ) can be used.

1 shows a motor driven pump 2 , whose pressure path / pressure side 4 via an electromagnetically controllable, normally open 2/2 way valve 6 and a hydraulic connection 8th with a low pressure accumulator 10 connected is. "Low pressure accumulator" in this context refers to a hydraulic accumulator with a mean pressure level in the order of a brake pressure ie between about 2000 and 10,000 kPa and is not to be confused with the known in the brake system technology ordinary low-pressure accumulator, usually in the range of 100 to 200 kPa is operated. The low pressure accumulator 10 is via one (or more) hydraulic line (s) with one (or more) consumer (s) 14 connected. In the pipe section 8th is a high-pressure accumulator 16 arranged, which is a normally closed 2/2-way valve 18 upstream.

By opening the 2/2-way valve 18 can by means of the pump 2 rechargeable high-pressure accumulator 16 to supply the consumer 14 be used with increased pressure. A check valve 20 that in the connection between the low pressure accumulator 10 and the high pressure accumulator 16 is arranged, prevents backflow of the pressure medium. Excess pressure medium, depending on a function to be processed or pressure control task, from the consumer 14 in a pressureless container 22 be drained. On the suction side 23 the pump 2 the pressure medium required is the pressure-free container 22 taken. As a result, the pressure medium circuit is closed.

The pressure side is the pump 2 with an additional hydraulic line 24 equipped after the check valve 20 in the connection to the consumer 14 opens and the pump 2 an immediate supply to the consumer 14 allows, if the low pressure accumulator 10 or the high-pressure accumulator 16 can not or should not contribute to the supply of pressure. For example, this construction allows the pump 2 for the basic supply of the consumer 14 to use.

By the described construction, it is also possible, a plurality of pressure sources (pump 2 , Low pressure accumulator 10 , High-pressure accumulator 16 ) independently of each other and coordinated depending on the actual prevailing operating conditions and the respective pressure medium requirement of the consumer (s) to control or to fill as desired with pressure medium.

In this context should be mentioned that in this embodiment (as with the other embodiments) additionally an electronic control unit, not shown, sensors, in particular Pressure sensors and other components are provided to electronically To fulfill regulatory tasks. Especially in braking systems is also an additional, by the driver Applied pressure controllable switching makes sense to even at failed electronics high supply pressure for the consumer (like brake booster) to be able to call.

In the embodiment according to 2 is a suction path 23 a motor driven pump 2 with a pressureless (ie under atmospheric pressure) container 22 connected. On her print page 4 is the pump 2 over a connection 8th with a low pressure accumulator 10 and a consumer 14 connected. In the connection is a check valve 20 installed, which prevents a pressure fluid reflux.

In addition to the possible basic basic supply by means of the pump 2 and the low pressure accumulator 10 is in the connection an additional supply circuit with an additional, driven by a hydraulic motor, pump 26 involved. This will allow the pump 2 or the low pressure accumulator 10 for driving the additional hydromotor driven pump 26 can be used. The additional hydromotor driven pump 26 has a drive path 28 with a normally closed 2/2-way valve 30 and a print path 32 which both in to the consumer 14 lead the leading connection. The placement of the junction of the pressure path 32 in the connection is chosen so that by virtue of the check valve 20 a backflow of the pressure medium in the direction of the suction path 28 is prevented. In the print path 32 is the high pressure accumulator 16 and a normally closed 2/2-way valve 18 , about which the required pressure medium if necessary to the consumer 14 can get. The consumer 14 is via a return line to the non-pressurized container 22 connected.

By this hydraulic circuit, the high pressure by means of the hydraulically driven pump 26 generated, the drive energy required for high pressure generation the low-pressure accumulator 10 taken with basic pressure.

The embodiment of the 3 shows an advantageous embodiment with reduced construction costs, in this embodiment, in particular a high-pressure accumulator is not required. A motor driven pump 2 is on the suction side 23 with a pressureless container 22 connected. On the print side 4 is the pump 2 via a hydraulic connection 8th into which a low pressure accumulator 10 is switched, via a check valve 20 with a consumer 14 connected. From the connection 8th branches a hydraulic connection 28 from, into the via a normally closed 2/2-way valve 30 a hydraulically driven pump 26 is switchable. On its pressure side is the pump 26 over a line 32 with the consumer 14 connected. The consumer 14 is via a return line to the non-pressurized container 22 in connection.

The normally closed 2/2-way valve 30 (which also after the pump 26 can be arranged) controls the drive volume flow of the hydraulically driven pump 26 , When the valve is closed 30 becomes the consumer 14 with the electric motor driven pump 2 supplied basic pressure supplied. With the valve open 30 increases the hydraulically driven pump 26 the supply pressure.

One opposite to the embodiment according to 3 largely identically constructed, but still further simplified version shows the 4 , An electric motor driven pump 2 promotes a connection 8th and a check valve 20 to a consumer 14 , The hydraulically driven additional pump 26 is a normally closed 2/2-way valve 30 downstream. In this embodiment, not the drive volume flow of the pump 26 controlled, but the output volume flow in the pressure path. The hydraulically driven pump 26 is in this case such that when interrupted flow volume flow and no drive volume flow occurs. The flow rate can be before or after the pump 26 to be interrupted.

5 shows a hydraulic linear drive according to the invention 50 , as a hydraulic motor pump unit z. B. in connection with the electrohydraulic power supply according to the invention and in particular the embodiments of the 2 to 4 can be used advantageously used. Also z. B. for driving a return pump, the linear drive is advantageously used.

The structure and mode of action of the hydraulic linear drive 50 are as follows: The drive has a housing 52 on, with a stepped bore 54 , In the hole 54 are two relatively displaceable, graduated pistons 56 . 58 with differently sized trained, circular or annular effective cross-sections 60 . 62 respectively. 64 . 66 . 68 arranged. Every piston 56 . 58 is by a spring 70 respectively. 72 resiliently biased resiliently and is in its normal position to a respective housing-side stop 74 respectively. 75 at.

The graduated piston 56 separates the rooms 76 . 78 and 79 from each other, the rooms 76 and 79 through a hole 94 in the piston 56 permanently connected to each other. The piston 58 is designed so gradual that the rooms 79 . 80 and 82 are separated from each other.

To reverse the movement of the piston 56 is a hydraulic valve 84 in the upper part of the housing 52 arranged, which is designed as a seat valve. One in the piston 56 on the same axis as the valve 84 arranged, likewise designed as a seat valve valve 86 serves to reverse the movement of the piston 58 , Furthermore, in the lower part of the housing 52 check valves 88 . 90 arranged the room 82 limit.

The piston 56 of the linear drive 50 is via a pressure fluid supply hole 92 acted upon by pressure medium (eg from the pump 2 or the low-pressure accumulator 10 in the in the 2 to 4 illustrated embodiments). The pressure medium acts in the illustrated position of the linear drive 50 on the effective cross-section 62 of the piston 56 and over the seat valve 86 and an axially parallel bore 94 on the effective cross-section 60 of the piston 56 , Out of the room 76 can the pressure medium over a Druckmittelabführbohrung 96 be recirculated (eg the container 22 in the 2 to 4 illustrated embodiments).

In the room 79 the pressure medium acts on the effective cross-section 66 of the piston 58 , As a result, the piston will be against the force of the spring 72 moves, leaving an over a Druckmittelzuführbohrung 98 and the check valve 88 supplied pressure medium over an example, but not necessarily on the same axis as the Druckmittelzuführbohrung 98 arranged Druckmittelabführbohrung 100 and the check valve 90 out of the room 82 is pumped into a pump or consumer circuit (eg to the consumer 14 in the 2 to 4 illustrated embodiments). As a result of the (pumping) movement of the piston 58 eventually becomes the seat valve 86 closed, causing the piston 56 against the force of the spring 70 is moved. This is the seat valve 84 opened and the pressure medium is discharged via the seat valve and the Druckmittelabführbohrung. Because the pressure in the room 79 is reduced, the piston moves 58 due to the force of the spring 70 back up making the (pump) room 82 enlarged and pressure medium is sucked. In the course of this movement reaches the piston 58 a position in which he has the seat valve 86 opens again, so that finally the illustrated starting position is reached again.

In other words, the hydraulic seat valves control 84 . 86 the drive volume flow as a function of the piston positions such that a self-sustaining, periodic sequence of movements arises. The reciprocating motion of the piston 58 acts like a reciprocating pump. In this way, a hydraulic motor-pump unit is realized in which the driving and the conveyed pressure medium are separated from each other, so that the unit advantageous z. B. can also be used in brake systems. The drive allows a Kreistrennung and a hydraulic decoupling, which as a result of a pressure medium supply in a primary or drive circuit by means of the drive, a pumping action in a separate secondary or pumping circuit is achieved.

2

pump

4

Print path / pressure side

6

2/2 way valve

8th

line section

10

Low-pressure accumulator

12

hydraulic connection

14

consumer

16

High-pressure accumulator

18

2/2 way valve

20

check valve

22

unpressurized container

23

suction

24

hydraulic management

26

hydraulic driven pump

28

drive path

30

2/2 way valve

32

print path

50

hydraulic linear actuator

52

casing

54

drilling

56 58

piston

60 62, 64

Effective cross section

66 68

Effective cross section

70 72

feather

74 75

attack

76 78, 79

room

80 82

room

84 86

poppet valve

88 90

check valve

92

Druckmittelzuführbohrung

94

drilling

96

Druckmittelabführbohrung

98

Druckmittelzuführbohrung

100

Druckmittelabführbohrung

Claims (11)

Electrohydraulic power supply for at least one consumer, with a first, motor-driven pressure source and at least a first pressure accumulator for the pressure supply of the consumer (s), characterized in that at least one further pressure source ( 26 ) or another accumulator ( 16 ), the first pressure source ( 2 ) or the first accumulator ( 10 ) the consumer (s) ( 14 ) to a first pressure level sufficient for a particular application and that the further pressure source ( 26 ) or the further accumulator ( 16 ) the consumer (s) ( 14 ) to a second, higher pressure level sufficient for a wider range of applications with higher pressure levels. Electrohydraulic power supply according to claim 1, characterized in that at least one of the pressure sources by a hydraulically driven pump ( 26 ) is formed. Electrohydraulic power supply according to one of the preceding claims, characterized in that the hydraulically driven pump ( 26 ) is provided for generating the higher pressure level. Electrohydraulic power supply according to one of the preceding claims, characterized in that for the connectability of the pressure source (s) ( 2 . 26 ) or the accumulator ( 10 . 16 ) electrically switchable valves ( 6 . 18 . 30 ) intended are. Electrohydraulic power supply according to one of the preceding claims, characterized in that the drive or the delivery volume flow of the hydraulically driven pump ( 26 ) driving hydraulic motor is controllable. Electrohydraulic power supply after one of the preceding claims, characterized in that the one or the consumer a Braking system of a vehicle is. Electrohydraulic power supply according to claim 4, characterized in that the electrically switchable valve ( 30 ) is switchable in response to a demanded by the driver of a vehicle brake request. Linear hydraulic drive with a first piston, a second (pump) piston and two valves for controlling the piston movements, characterized in that the valves ( 84 . 86 ) are designed as seat valves. Linear hydraulic drive according to claim 8, characterized in that the valves ( 84 . 86 ) are arranged on the same axis, in particular the housing center axis. Linear hydraulic drive according to one of claims 8 or 9, characterized in that the pistons ( 56 . 58 ) and the valves ( 84 . 86 ) in a common housing ( 52 ) are arranged. Linear hydraulic drive according to claim 8, 9 or 10, characterized in that the linear drive ( 50 ) Is part of a braking system.